In the trucking industry, it is common to cover the open cargo or container area of a truck using a covering system to prevent spillage onto the roadway or to retain heat in the case of asphalt. The covering system is typically a tarping system. There are many tarping systems with a variety of deployment means. All such systems have a common spring-loaded roller that maintains tension on the tarpaulin and which stores the tarp or cover when the container is uncovered. In a typical system, the tarp is attached to the roller at one end while the other is fixed to a stationary member of the covering system. The roller is typically attached to a bail member that is rotatable relative to the container to move the tarp between covered and uncovered positions.
The typical bail member includes a pair of arms each pivotably attached at one end to the truck or to the container and attached at an opposite end to the tarp roller. The typical bail member also includes at least one spiral torsion spring that can have a reaction end anchored to a base mount on the truck or the container and can have an opposite reaction end anchored to the arm in order to exert a torsion force in the deployed direction. This force serves to aid in moving the cover to a deployed position and to prevent the cover from lifting off the container in a deployed position. In order to exert a force in the deployed direction, the spring must first be pre-loaded.
Typically, the way the spring is pre-loaded consists of turning the base mount while holding the bail arms stationary. When the required amount of pre-load has been accomplished, the mount is attached to the container. The typical base mount has a single set of mounting holes that only allow the mount to be attached to the container in one position. In order to adjust the pre-load on the spring it is typically necessary to drill additional holes either in the mount or the container, or to weld the mount to the container without using the mounting holes.
U.S. Pat. No. 6,575,519, issued to Henning, discloses an actuation mechanism for a tarping system. The '519 patent includes a shaft bracket mountable to a side of a truck and including a mounting plate and a shaft. The shaft defines an anchor slot extending along a substantial portion of the length of the shaft in order to anchor a center portion of a double coil spiral spring. Also, the shaft is pivotally attachable to a bail member of a covering system. The mounting plate includes an array of three pairs of mounting holes with a hole in each pair being located opposite to the other hole in the pair relative to the shaft. The three pairs of mounting holes allow the shaft bracket to be attached to the truck and allows for a limited number and range of different angular orientations of the anchor slot relative to the truck.